Charged-particle accelerating device for metric wave operation

Abstract

The particle-accelerating device comprises a charged-particle source, a linear accelerating structure formed by a series of accelerating resonant cavities, an electromagnetic wave generator for emitting a signal to be injected into at least one of the resonant cavities. Means are provided for applying a pulsed high voltage to the particle source and for scanning a target with the pulsed beam of accelerated particles. The electromagnetic wave generator comprises a thermionic tube having a cathode, an anode and at least one grid. At least one of the resonant cavities is electromagnetically coupled to the grid-anode space of the tube.

What is claimed is: 
     
       1. A charged-particle accelerating device for metric wave-length operation comprising a source of charged particles, a linear accelerator having a series of resonant cavities for accelerating a beam of said charged particles and means in said cavities for focusing said beam, an electromagnetic wave generator for emitting a signal and injecting said signal into a least one of said resonant cavities, means for applying a pulsed high voltage to the particle source to produce said particles, and means for scanning a target with the beam of accelerated particles, wherein the electromagnetic wave generator comprises a thermionic tube provided with a cathode, an anode and at least one grid, at least one of the resonant cavities of the accelerating structure being electromagnetically coupled to the grid-anode space of the tube. 
     
     
       2. A particle-accelerating device according to claim 1, wherein the tube is an oscillating triode G. 
     
     
       3. A particle-accelerating device according to claim 1, wherein the tube is an oscillating tetrode. 
     
     
       4. A particle-accelerating device according to claim 1, wherein the generator is an amplifying tube associated with a control oscillator having a frequency f equal to the resonance frequency of the resonant cavities of the accelerating structure. 
     
     
       5. A particle-accelerating device according to claim 2, wherein the triode G which comprises a coaxial line of adjustable length associated with the grid-anode space and a coaxial line of adjustable length associated with the cathode-grid space is electromagnetically coupled to one of the resonant cavities of the accelerating structure by means of a loop and wherein a movable plunger provides a capacitive coupling between the coaxial lines. 
     
     
       6. A particle-accelerating device according to claim 2, wherein the triode G which comprises a coaxial line of adjustable length associated with the grid-anode space and a coaxial line associated with the cathode-grid space is provided with coupling means on the one hand for electromagnetically coupling the coaxial line to a first cavity of the accelerating structure and on the other hand for electromagnetically coupling the coaxial line to a second cavity of said accelerating structure which immediately follows the first cavity so as to ensure that the cathode-grid space of the triode is excited in phase opposition with respect to the grid-anode space, the accelerating structure being of the biperiodic type. 
     
     
       7. A particle-accelerating device according to claim 1, wherein the system for scanning the accelerated-particle beam serves to scan the width of a target Z at each pulse of said accelerated-particle beam. 
     
     
       8. A particle-accelerating device according to claim 7, wherein said device comprises: a modulator for applying a pulsed high voltage to the cathode of the accelerator;   
     
     
       a modulator for applying a pulsed high voltage to the anode of the triode; 
     
     
       a generator for delivering a sinusoidal voltage which is intended to be applied to a scanning electromagnet; 
     
     
       a device for triggering the pulses of the modulators, the function of the generator aforesaid being to control the initial operation of the device. 
     
     
       9. A device according to claim 1 and comprising a linear accelerating structure formed by a series of metal tubes of cylindrical shape having an axis X--X and by circular plates placed at right angles to said axis X--X, wherein annular elements are fixed respectively on each side of each plate aforesaid and wherein said elements are of increasing thickness from the peripheral zone to the central zone thereof, and wherein the shape of said annular elements is such as to form an annular housing on the face located opposite to each plate with which each element is associated, said annular housing being intended to accommodate a magnetic coil.